[Dnsmasq-discuss] Disabling dynamic DHCP assignment for known hosts
Simon Kelley
simon at thekelleys.org.uk
Sun Apr 30 18:23:05 BST 2017
I just committed a patch to do this. I chose the tag "known-othernet"
just because it seemed more descriptive.
Cheers,
Simon.
On 19/04/17 19:36, Todd Sankey wrote:
> I tried a different approach. I created a patch (attached) so that the
> tag "knownother" is applied if there is a host definition that applies
> to a different context. In our setup, we then added
> "dhcp-ignore=tag:knownother".
>
> On Wed, Mar 15, 2017 at 1:14 PM, Todd Sankey <dev at lutean.com
> <mailto:dev at lutean.com>> wrote:
>
> Our setup has two wifi networks with different network addresses,
> one for employees and one for guests. On the employee network, the
> hosts all have static host entries that include IP addresses. The
> guest network has no static host entries. What we would like to do
> is prevent the employee machines from getting any assignment on the
> guest network.
>
> We tried using "tag:!known" in the dhcp-range configuration, and we
> have tried a tag-if statement that sets a tag based on the guest
> network interface and known followed by a dhcp-ignore. Neither works.
>
> Looking through the code, I think it is because when looking for a
> dhcp_config entry, the search is filtered by whether the assigned
> address is valid for the interface the request was received on.
> Since the static assignments are only valid for the employee
> network, when a request is received on the guest network, the static
> assignments are not valid so the "known" tag is never set. As a
> result, neither the dhcp-range tag filter nor the tag-if filter has
> the desired effect.
>
> I next tried having dhcp-host entries for every employee machine,
> one with a static assignment on the employee network, and one with a
> static assignment on guest network and appending "ignore" to the
> guest network entry. This seems to have the desired behaviour in
> that employee machines cannot get on the guest network. However,
> this obviously doubles the work of maintaining the host list. I am
> also not sure what this does to the guest address range having these
> static but ignored assignments.
>
> Is there a better way to do this in the current version (2.76)?
>
> If not, would it be a reasonable feature request to extend the
> handling of dhcp-host settings so that if there is an IP assignment
> and "ignore" is specified, then the host is ignored on networks
> where the IP assignment is not valid?
>
>
>
>
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